ALMA-IRDC - II. First high-angular resolution measurements of the N-14/N-15 ratio in a large sample of infrared-dark cloud cores
Artikel i vetenskaplig tidskrift, 2021

The N-14/N-15 ratio in molecules exhibits a large variation in star-forming regions, especially when measured from N2H+ isotopologues. However, there are only a few studies performed at high-angular resolution. We present the first interferometric survey of the N-14/N-15 ratio in N2H+ obtained with Atacama Large Millimeter Array observations towards four infrared-dark clouds harbouring 3 mm continuum cores associated with different physical properties. We detect (NNH+)-N-15 (1-0) in of the cores, depending on the host cloud. The N-14/N-15 values measured towards the millimetre continuum cores range from a minimum of similar to 80 up to a maximum of similar to 400. The spread of values is narrower than that found in any previous single-dish survey of high-mass star-forming regions and than that obtained using the total power data only. This suggests that the N-14/N-15 ratio is on average higher in the diffuse gaseous envelope of the cores and stresses the need for high-angular resolution maps to measure correctly the N-14/N-15 ratio in dense cores embedded in IRDCs. The average N-14/N-15 ratio of similar to 210 is also lower than the interstellar value at the Galactocentric distance of the clouds (similar to 300-330), although the sensitivity of our observations does not allow us to unveil N-14/N-15 ratios higher than similar to 400. No clear trend is found between the N-14/N-15 ratio and the core physical properties. We find only a tentative positive trend between N-14/N-15 and H-2 column density. However, firmer conclusions can be drawn only with higher sensitivity measurements.

stars: formation

ISM: clouds

ISM: molecules


F. Fontani

Istituto nazionale di astrofisica (INAF)

Max-Planck-Institut für extraterrestrische Physik

A. T. Barnes

Universität Bonn

P. Caselli

Max-Planck-Institut für extraterrestrische Physik

J. D. Henshaw


Giuliana Cosentino

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Extragalaktisk astrofysik

I Jimenez-Serra

Centro de Astrobiología (INTA-CSIC)

Jonathan Tan

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

J. E. Pineda

Max-Planck-Institut für extraterrestrische Physik

Chi Yan Law

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Extragalaktisk astrofysik

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 503 3 4320-4335


Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik

Annan fysik



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